Hydraulic expansible rotary well drilling bit



IFeb. 3, 1959 c. H. BARG 2,872,160

HYDRAULIC ExRANsIBLE ROTARY WELL DRILLING BIT Filed May 14,1956

EGOL C NRW.

41( 40 mwmu,

HYDRAULIC EXPANSIBLE ROTARY WELL DRILLENG BIT Application May 14, 1956, Serial No. 584,650

Claims. (Cl. Z55-76) The present invention relates to rotary well drilling bits, and more particularly to bits of the expansible type capable of being lowered in a well casing and of having a larger effective drilling diameter than the inside diameter of the well casing.

An object of the present invention is to provide an improved hydraulically expansible rotary drill bit capable of discharging drilling iiuid at the bottom of the bit, to insure the upward iiushing and removal of the cuttings to the top of the well bore.

VAnother object of the invention is to provide an expansible drill bit having cutters expanded outwardly by hydraulic pressure and retracted by a spring device, in which the spring device is readily acceptable, being easily installed in the bit and removed therefrom.

A further object of the invention is to provide a hydraulically expansible rotary drill bit, in which the cutters are shifted to retracted position by a spring device, and in which the spring device is protected from the drilling lluid being pumped through the device as well as from the cuttings produced by the drill bit.

An additional object of the invention is to provide a hydraulically expansible rotary drill bit, in which drilling fluid is pumped through and discharged from the bit, the discharging or exhausting uid being availed of to assist in the expansion of the drill bit cutters.

This invention possesses many other advantages, and has other objects which may be made more clearly apparent from a consideration of a form in which it may be embodied. This form is shown in the drawings accompanying and forming part of the present specication. It will now be described in detail, for the purpose i of illustrating the general principlesof the invention;

but it is to be understood that such detailed description is not to be taken in a limiting sense, since the scope of the invention is best defined by the appended claims.

Referring to the drawings:

Figure l is a longitudinal section, with some parts shown in side elevation, through a rotary drill bit disposed in a well bore, with its cutters in expanded condition; Fig. 2 is a cross-section taken along the line 2--2 on Fig. 1',

Fig. 3 is a fragmentary longitudinal section illustrating one of the cutters in its retracted position;

Fig. 4 is an isometric projection of the inner portion of avcutter blade. As disclosed in the drawings, a rotary drill bit A is adapted to be lowered in a string of well casing (not shown), or the like, to a point below its lower end where an existing well bore is to be enlarged in diameter.Y The tool will enlarge the wellbore and then operate upon a transverse formation shoulder B,V whic h its cutters produce, to continue the hole enlargement in a downward direction as the tool is lowered on a string of drill pipe C extending to the top of the well bore.

VAlthough the apparatus disclosed will be described arent with particular reference to enlarging the diameter of a l 2,872,160 Patented Feb.Y 3, 1959 well bore below a string of well casing, it is to be understood that the tool can be used for other purposes in the well bore, such as for severing andmilling away a length of casing disposed therewithin.

v The specilic apparatus illustrated includes an elongate tubular main body 10 having a threaded box 11 at its upper end, which enables the body to be threadedly secured to the lower end 4of a string of drill pipe C extending to the top of the hole. The lower portion 12 of the body may be tapered to serve as a guide in preventing the body from hanging up on obstructions or restrictions in the well casing, or the well bore therebelow.

The body has a plurality of elongate slots 13 therein, each of which contains a cutter blade 14Y pivotally mounted on a hinge or pivot pin 15 extending transversely across the upper portion 16 of the slot, which is of less width than the lower portion 17, as explained hereinbelow. The hinge pin 15 has a relatively smooth shank 1S extending through theblade and into a cylindrical bore or recess 19 at one side of the slot, the opposite end of the hinge pin having athreaded head 20 received within a threaded bore 21 in the main body of the tool at the other side of the slot.

Each blade 14 is movable from a retracted position (Fig. 3), in which it depends within the slot 13 almost completely within the contines of the periphery of the body 10, to an expanded position (Fig. l), in which it engages a stop lug 22 at the upper end of the slot. The lug 22 is received within a recess 23 in the body above the slot i3, this stop lug being suitably secured to the body by a cap screw 24. Each blade 14, when engaging the stop lug 22, has its lower cutting edge 25 substantially normal to the body axis. When disposed in Ya fully retracted position, the lower cutting edge 25, referred to above, will be disposedin its Vinward position substantially parallel toy the axis of the body, as disclosed in Fig. 3. v

Each blade 14 has an inner portion 26 slidable along the leading and trailing walls 27, 28 of the upper slot 16, such inner portion 26 lying in a central plane radial of the axis of the tool. From the inner portion, an outer blade portion 29 extends, disposed at an angle to theV inner portion,v the leading face 30 of the Aouter portion lying on a plane substantially radial of the axis of the body. In view of the angular disposition of the outer blade portion 29 with respect to the inner blade portion 26, the lower slot portion 17 is wider than the upper slot portion 16, its trailing side 28 being coincident with the trailing side of the upper slot portion, but its leading side 27a extending substantially forwardly of the correspondingly leading side 27 of the upper slot portion 16, as disclosed most clearly at the left portion of Fig. 1.

The cutters or blades 14 are initially disposed in ,their retracted position, such as shown in Fig. 3. 4Theyare adapted to be expanded outwardly to their fullest extent into engagement with the stop lugs 22 by a rack and pinion device. Thus, a rack 31 is formed as a series of circular gear teeth on a plunger tube 32 disposed within the body passage 33, the upper end of this tube being threadedly secured to an upper plunger head 34 slidable' within an upper cylinder or passage portion 35 of the body. The lower end of the plunger rack 32 is threadedlyy secured within a lower tubular headl 36 slidablewithin'y the lower portion of the body bore or passage 33.r Thisprevented from inadvertent unthreading or removal from the body by a lock screw threaded transversely in the body wall, its inner portion engaging a slot or recess 41 inthe lower end of the spring seat.

The upper plunger head 34, plunger tube 32, lower plunger head 36 and tubular guide 37 are normally urged in an upward direction by a helical compression spring 42 disposed within the spring chamber 38, with its upper end engaging the lower tubular head 36 and its lower end engaging the spring seat 39. When in its upper position, the rack teeth 31 will locate the cutter blades 14 in a fully retracted position within the body slots 13, by virtue of the meshing of the circular rack teeth 31 with a gear sector 43 formed on the inner portion or quadrant of each cutter blade.

Normally, the spring 42 holds the plunger device in an elevated position, with the cutters in their retracted location within the body slots, the lower rack tooth engaging the bottom sector teeth on each cutter (Fig. 3). It is to be noted that the passage 44 through the plunger apparatus has a substantially smaller diameter than the passage 45 through the upper portion of the body. Accordingly, duid pumped down through the drill pipe C will have its flow restricted, as a result of entering the passage 44, building up a back pressure tending to shift the plunger apparatus 34, 32, 36, 37 in a downward direction within the body. When the back pressure is sufcient in extent to overcome the force of the spring 42, it will move the plunger device down, causing the rack teeth 31 to engage the gear sectors 43 and swing the cutters 14 in an outward direction, to the extent limited by engagement of the upper edges of the cutters with the stop lugs 22 at theupper ends of the body slots 13. When in such fully expanded condition, the spring 42 will have been compressed to a much greater extent. When thepressureis relieved, therspring 42 can shift the vplunger apparatus upwardly back to its initial position, which will swing the cutter blades 14 inwardly to their fully retracted position. v l

To prevent leakage of duid between the upper plunger head 34 and the wall of the body passage 35, a suitable side seal ring 51 is secured'in a ring groove S2 in the upper head, this ring slidably sealing against the wall of the body passage. As disclosed, this seal S1 is of the lip type, having an upwardly facing lip 53, which will be urged by fluid pressure thereabove outwardly against the wall of the body passage 35. Similarly, a seal ring 54 is provided between the lower head 36 and the wall of the lower passage portion 33, this seal being disposedwithin a groove 55 in the head and slidingly and sealingly engaging the passage wall. Here again, the seal ring lSlvmay be of the lip type with the lip 56 facing in an upward direction, so as to prevent external lluid above the head from passing downwardly along its periphery into the spring chamber 38 therebelow. The tube guide 37 does not make a fluid-tight sliding lit with the spring seat 39, for a reason that will be described hereinbelow.

During the hole enlarging operation, `drilling weight is l being transmitted directly from the body 10 of the tool to the upper portions of the blades 14, and from the lower, cutting portions of the blades to the formation shoulder B. The drilling torque is being transmitted from the trailing sides 2S of the slots 1,6 to the portions of ,the rear faces 60 of the upper blade portions 26 that are disposed outwardly of the axes of the hinge pins 15. However, the leading faces 61 of the blades on the other Y side of the hinge `pin axes are being forced by the drilling which extends across the ends of the teeth 43, the leading face of the flange 62 lying in the same plane as the leading face 61 of the inner portion of each blade, with its lower edge 63 lying in the same plane as the lower edge 25 of the blade. The ange 62 extends substantially across the whole width of the blade 14 and inwardly of the gear teeth 43, terminating iust short of the circular rack teeth 31 on the tubular plunger 32, so as to avoid interference with the latter.

Each flange 62 materially increases the bearing surface between the leading face of each blade and the leading side 27 ot the body dening the slot 13 in which the blade is contained. Without interfering with the action of the rack and pinion, it still permits the gear sector teeth 43 to have substantial length and a large bearing contact with the circular rack teeth 31.

In using the apparatus, the blades 14 are initially located in their retracted positions, inasmuch as the spring 42 maintains the plunger device in its upward position within the body passage. The apparatus A is lowered through the well casing on the drill pipe C to a location below the lower end of the casing at which theV well bore is to be enlarged in diameter. The drill pipe C andthe expansible drill bit A are then rotated at the proper speed, and iluid under pressure is pumped down through the drill pipe and into the body passage 45. As explained above, the restricted area through the plunger passages 44 causes a back pressure to be built up in the body passage 45 thereabove, which, when suflicient, urges the plunger device 34, 32, 36, 37 downwardly against the force of the spring 42, causing the rack 31 to swing the blades 14 in an upward and outward direction. The blades 14 will engage the wall of the original hole, which will oler resistance to their outward movement. However, the rotation of the drill pipe C, body 10 and blades 14 will cause the latter to remove formation material, until the blades have been expanded outwardly to their fullest extent, such as disclosed in Fig. l. When in this position, down weight of the proper amount can be imposed on the drill pipe C and body 1t) of the tool, the downward force being transmitted through the body and its stop lugs 22 to the upper parts of the cutters 14, forcing their lower edges 25 against the transverse shoulder B which has been formed by the cutters in the well bore as a result of their outward expansion. The drill pipe and body are rotated, with duid being continuously pumped through the apparatus, this fluid passing down through the tubular plunger device and discharging from the lower end of the tube or guide 37, the drilling iluid then passing upwardly around the body 10 of the tool to carry the cuttings upwardly through the annulus around the drill pipe C ,to the top of the hole. Actually, duid pressure is not necessary to the maintenance of the cutters or blades 114 in their fully expanded condition, since they will be held in this position by the drilling weights imposed on the body 10 and the cutters 14.

Whenever itis desired yto retract the cutters 14, the pressure of iluid in the drill pipe C and the body passages 44, 45 is relieved, and the tool A elevated above the formation shoulder B, which then allows the compression spring 42 to expand and shift the plunger device upwardly, causing its rack teeth 31 to operate upon the gear sector teeth 43 and swing the blades 14 in a downward and inward direction to the fullest extent within the body lots 13. The tool A can now be withdrawn from the well bore, if desired.

lt is to beY noted that the body slots 13 extend completely through the wall of the body 10, which will allow wider blades 14 to be used, since they can be disposed adjacent the plunger tube 32 when in their fully retracted position, the periphery of the tube 32 being spaced inwardly from the inner wall of the body passage 33'.

, By locating the spring 42 in the confined spring chamber 38 at the lower portion of the body, the accessibility of the spring is considerably enhanced.Y In assembling the apparatus, `the plunger device 34, 32, 36, 37 can be inserted into position through the upper end of the body passage 45, 33. The blades 14 can then be moved into the slots 13 with their gear teeth 43 meshed appropriately with the circular rack teeth 31 on the plunger tube 32, after which the hinge or pivot pins 15 are placed transversely within the body bores 21, 19 and through the holes in the blades. The spring 42 can then be slipped upwardly around the guide tube 37, into the spring chamber 38, followed by the spring seat 39, which will be screwed into place by means of an appropriate tool, after which the locl: screw 4i) can be assembled to the body with its inner end extending into the spring seat slot 41, locking the latter in its proper position. The spring 42 will, at this time, exert an upward force tending to hold the cutters 14 in their retracted position.

During the pumping of the fluid through the apparatus, it is to be noted that the spring 42 is protected from the Huid, which is actually prevented from entering the spring chamber 33, inasmuch as the fluid is discharged through the lower end of the tube guide 37, which is then extending almost completely through the spring seat 39, as shown in Fig. l. In addition, the Huid and cuttings cannot pass into the spring chamber 38 from a location thereabove in view of the provision of the seal ring 54 in the lower head 36. As a matter of fact, the fluid discharging from the guide tube 37 creates a suction effect in the spring chamber 38, tending to draw the iluid outwardly thereof and creating a partial vacuum therein, which tends to assist the action of the fluid pressure on the upper end of the upper plunger head 34 in expanding the cutters 14 from their retracted to their fully extended positions.

In addition to directing the uid to the lower portion of the tool, so as to be assured that all the cuttings will lbe flushed upwardly to the top of the hole, assurance can be had that the cutter blades 14 are not impeded by the presence of cuttings on the formation shoulder B on which the blades are operating. In the present instance, a plurality of nozzles 7@ is provided, which can discharge uid directly upon the formation shoulder B, and immediately in advance of the cutter blades 14, or for that matter, also upon the leading faces 30 of the cutting blades themselves. As disclosed, a plurality of inclined nozzle passages 71 are formed in the upper portion of the body 10 above the upper plunger head 34, each passage having an inlet 72 opening into the central body passage 45 and an outlet 73 opening through the periphery of the body. A nozzle 7i) is inserted upwardly in each passage 71, the nozzle having a shoulder 74 engaging a gasket or seal ring 75, made of rubber or rubber-like material, which, in turn, bears against a body shoulder 76, to prevent fluid leakage around the exterior of each nozzle 7d. The nozzle is held in assembled position by a set screw 77 threaded in a radial hole 78 in the body of the tool and received within a peripheral groove 79' in the periphery of the nozzle.

The drilling fluid, in addition to being pumped down through the plunger passage 44 for discharge at the lower end of the tool, also passes through the nozzle passages $0, which jet the drilling duid directly upon the formation shoulder B immediately in advance of the cutter blades 14, or also partially. upon the leading faces of the cutter blades, to maintain the shoulder B and the blades 14 free from cuttings, and to assist in'flushing the cuttings to the top of the well bore. In this manner, the progress of the expansible drill bit is not impeded by any necessity for the blades to ride upon a loose mass of previously produced cuttings.

The tubular guide 37 may be constituted as a circulation bean or orifice by decreasing its internal diameter with respect to the diameters of the passages through the upper plunger head 34, plunger tube 32, and the lower head 36. Thus, the back pressure built up in the passage 6 45 above the upper plunger head 34can be varied merely by preselecting a bean or guide 37 having the desired internal diameter. This bean 37 can be changed easily by unscrewing it from the head 36 through the lower end of the body 10 and substituting a diterent bean for it.

The inventor claims:

l. In a rotary drill bit: a tbody having a central passage and adapted to be connected to a drill string, said passage opening through the lower end of said body; cutter means mounted on said body for expansion laterally outward of said body; means for expanding said cutter means laterally outward of said body, including a plunger movable downwardly in said passage in response to uid pressure in said passage; a spring seat movable upwardly into said passage through the lower end of said body; means for securing said seat to said body within said passage; and a spring above said seat engaging said seat and plunger to shift said plunger upwardly in said passage to retract said cutter means, said spring being removable from said passage through the lower end of said body.

2. l'n a rotary drill bit: a tbody having a central passage and adapted to be connected to a drill string, said passage opening through the lower end of said body; cutter means mounted on said body for expansion laterally outward of saidl body; means for expanding said cutter means laterally outward of said body, including a tubular plunger movable downwardly in said passage in response to fluid pressure in said passage; a spring seat movable upwardly into said passage through the lower end of said body; means for securing said seat to said body within said passage; said plunger being slidable in said seat; and a spring above said seat surrounding said plunger with its lower end engaging said seat and its upper end engaging said plunger to shift said plunger upwardly in said passage to retract said cutter means, said spring being removable from said passage through the lower end of said body.

3. in a rotary drill bit: a body having a central passage and a plurality of slots, said passage opening through the lower end of said body; cutter means mounted on said body in said slots for expansion laterally outward of said body; means for expanding said cutter means laterally outwardly of said body, including a tubular plunger movable downwardly in said passage in response to fluid pressure in said passage and sealingly engaging said body above and below said slots; a spring seat movable upwardly into said passage through the lower end of said body; means for securing said seat to said body within said passage; said plunger being slidable in said seat; and a spring in said passage above said seat surrounding said plunger with its lower end engaging said seat and its upper end engaging said plunger to shift said plunger upwardly in said passage to retract said cutter means, said spring being removable from said passage through the lower end of said body.

4. In a rotary drill bit: a body having a central passage and adapted to be connected to a drill string, said passage opening through the lower end of said body; cutter means mounted on said body for expansion laterally outward of said body, said cutter means having gear teeth thereon; a plunger having rack teeth thereon meshing with said gear teeth and movable downwardly in said passage in response to fluid pressure in said passage to expand said cutter means laterally outward of said body; a spring seat movable upwardly into said passage through the lower end of said body', means for securing said seat to said body within said passage; and a spring above said seat engaging said seat and plunger to shift said plunger upwardly in said passage to retract said cutter means, said spring being removable from said passage through the lower end of said body.

5. In a rotary drill bit: a body having a central passage and a plurality of slots, said passage opening through the lower end'of said body; cutter means mounted on said body Ain said slots for expansion laterally outward 'of Asaidbody, said cutter means having gear teeth thereon; a tubular plunger having rack teeth meshing with said gear teeth and movable downwardly in said passage in response to said uid pressure in said passage and sealingly engaging said body above and below said slots; a spring seat movable upwardly into said passage through the lower end of said body and then secured to said body; said plunger being slidable in said seat; and a spring surrounding said plunger with its lower end engaging said seat and its upper end engaging said plunger to shift said plunger upwardly in said passage to retract said cutter means.

6. In a rotary drill bit: a body having a central passage yand a plurality of slots; cutter means mounted on said body -in said slots for expansion laterally outward of said body; means for expanding said cutter means laterally outwardly of said body, including a plunger in Said passage having rack teeth thereon, said cutter means having gear teeth meshing with said rack teeth and expandible outwardly in response to downward movement of said plunger in said passage, said cutter means having bearing portions extending across and between end faces of said gear teeth and slidable along the leading faces of said slots.

7; In a rotary drill :bit: a body having a central passage and a plurality of slots; cutter means mounted on said body in said slots for expansion laterally outward of said body; means for expanding said cutter means laterally outwardly of said body, including a plunger in said passage having circular rack teeth thereon, said cutter means having gear teeth meshing with said rack teeth and expandible outwardly in response to downward movement of said plunger in said passage, said cutter means having bearing portions extending across and between end faces of said gear teeth substantially to said circular rack teeth and slidable along the leading faces of said slots.

8. In a rotary rdrill bit: a body having a central passage and aplurality of slots, said passage opening through the lower end of said body; cutter means mounted on said body in said slots for expansion laterally outward of said body; means for expanding said cutter means laterally outwardly ot said body, including a plunger in said passage having rack teeth thereon, said cutter means having gear teeth meshing with said rack teeth and expandible outwardly in response to downward move ment of said plunger in said passage, said cutter means having ybearing portions extending across and between end faces of said gear teeth and slidable along the leading faces of said slots; a spring seat movable upwardly into said passage through the lower end of said body and then secured to said body; said plunger being slidable in said seat; and a spring in said passage surrounding said plunger with its lower end engaging said seat and its upper end engaging said plunger to shift said plunger upwardly in said passage to retract said cutter means.

9, In a rotary drill bit: a body having a central passage and a plurality of slots, said passage opening through the lower -end of said body; cutter means mounted on said body in said slots for expansion laterally outward of said body; means for expanding said cutter means laterally outwardly of said body, including a plunger in said passage having circular rack teeth thereon, said cutter means having gear teeth meshing with said rack teeth and expandlble outwardly in response to downward movement of said plunger in said passage, said cutter moans having bearing portions extending across and between said faces of said gear teeth substantially to said circular raelt teeth and slidable along the leading faces oi said siots; a spring seat movable upwardly into said passage through the lower end of said body and then secured to said body; said plunger being slidable in said seat; and a spring in said passage surrounding said plunger with its lower end engaging said seat and its upper end engaging said plunger to shift said plunger upwardly in said passage to retract said cutter means.

lt). in a rotary drill bit: a body having a central passage and adapted to be connected to a drill string, said passage'opening through the lower end of said body; cutter means mounted on said body for expansion laterally outward of said body; means for expanding said cutter means laterally outward of said body, including a tubular plunger movable downwardly in said passage in response to fluid pressure in said passage; a spring seat movable upwardly into said passage through the lower end of 'said body and then secured to said body; said plunger including an upper portion and a lower portion slidable in said seat and detachably secured to said upper portion, said lower portion having a smaller inside diameter than the inside diameter of said upper portion; and a spring surrounding said lower portion with its lower end engaging said scat and its upper end engaging said upper portion to shift said plunger upwardly in said v passage to retract said cutter means; said lower portion being adapted to be detached from said upper portion and removed from said body through said seat and lower and of said passage.

References Cited in the tile of this patent UNITED STATES PATENTS 

